virtually

adv 1: (intensifier before a figurative expression) without

exaggeration; "our eyes were literally pinned to TV

during the Gulf war" [syn: {literally}]

2: in essence or effect but not in fact; "the strike virtually

paralyzed the city"; "I'm virtually broke"

3: (of actions or states) slightly short of or not quite

accomplished; "the job is (just) about done"; "the baby

was almost asleep when the alarm sounded"; "we're almost

finished"; "the car all but ran her down"; "he nearly

fainted"; "talked for nigh onto 2 hours"; "the recording

is well-nigh perfect"; "virtually all the parties signed

the contract"; (`near' is used informally for `nearly' as

in "I was near exhausted by the run"; `most' is used

informally for `almost' as in "most everybody agrees")

[syn: {about}, {just about}, {almost}, {most}, {all but},

{nearly}, {near}, {nigh}, {well-nigh}]

Virtual LAN

Software defined groups of {host} on a {local

area network} (LAN) that communicate as if they were on the

same wire, even though they are physically on different {LAN

segment}s throughout a site. To define a virtual LAN, the

{network administrator} uses a virtual LAN management utility

to establish membersip rules that determine which hostss are

in a specific virtual LAN. Many models may exist but two seem

to dominate:

(1) Vitual Segment (or Port-Group) Virtual LAN. These are

switched at the {data link layer} ({OSI} layer 2). Virtual

segments turn an arbitrary number of physical segments into a

single virtual segment that funtions as a self-contained

traffic domain.

(2) Virtual Subnet Virtual LAN: These are switched at the

{Network Layer} ({OSI} layer 3). Subnet-oriented virtual LANs

are based on {subnet address}es used by {IP}, {IPX}, and other

{network layer} {protocol}s to normally identify physical

networks. Administrators assign one subnet address to a

number of switch {port}s (which may be on different switches

and over a backbone). Once identified as a virtual subnet,

the selected LANs function as a {bridge group} - traffic is

bridged at Layer 2 within the virtual subnet and routed at

Layer 3 between virtual subnets.

["The many faces of virtual LANs", Steven King, Network

World, 1994/5?].

(1995-04-03)